P1148: REAL WORLD DATA (RWD) AMONG FOLLICULAR LYMPHOMA (FL) PATIENTS IN GERMANY WITH AT LEAST TWO PRIOR LINES OF SYSTEMIC THERAPY AND COMPARISON WITH CLINICAL DATA FOR MOSUNETUZUMAB
Authors: N. Marschner, J. Hanselmann, S. McGough, S. Braun, S. Pfizler-Dempfle, R. Sandner, J. Mohm, M. Jaber, D. Hamm, N. Hamm, M. Jaenicke, A. Shewade
Journal: HemaSphere (2022)

Background: FL is characterized by its indolent nature, with patients (pts) experiencing multiple relapses and successively poorer outcomes with each relapse (Link et al. 2019). Treatment with immunochemotherapy regimens has significantly improved outcomes in pts with newly diagnosed FL, but limited treatment options are available in Europe, with no standard of care for pts with multiple relapses, such as those who have received at least two prior lines of systemic therapy (3L+ FL). Mosunetuzumab (M) is a T-cell engaging CD20xCD3 bispecific antibody that has shown high rates of complete response and favorable safety in pts with 3L+ FL in a single-arm Phase II trial (NCT02500407; Budde et al. ASH 2021). RWD can provide relevant context to interpret data from the single-arm trial (SAT) of M as a treatment option in 3L+ FL. Aims: This study summarizes RWD in pts with 3L+ FL utilizing the Tumor Registry Lymphatic Neoplasms extension (TLNext) and plans to perform a matching-adjusted indirect comparison (MAIC) between the M SAT and TLNext. Methods: TLN was a multicenter, longitudinal, observational, prospective cohort study collecting data from medical charts of pts with lymphoid B-cell neoplasms receiving care at office-based hematology practices in Germany (NCT00889798; Knauf et al. 2019). Patients were enrolled between 2009–14 and followed for up to 5 years. TLNext collected additional data up to November 2021 from consented pts originally enrolled in TLN as well as additional newly-consented pts with 3L+ FL. Baseline characteristics, treatment patterns, and outcomes were summarized for pts with 3L+ FL in TLNext. A MAIC is planned between the M SAT and a TLNext cohort selected by applying key eligibility criteria from the M SAT. An index line of therapy (LoT) will be selected for all pts with more than one recorded LoT. Imbalance adjustment will be performed by re-weighting the TLNext cohort using weights determined from distributions of prognostic clinical factors observed in M SAT. Results: TLNext included 69 pts who had received 112 documented LoTs in 3L+ FL. Median follow-up was 40 months from the start of the 3rd LoT. 65 pts had received an anti-CD20 therapy and an alkylator therapy prior to index therapy and had a known relapse or refractory status (Table). Latest recorded LoT was selected as the index therapy for every patient. Compared to M SAT, the TLNext cohort was slightly older and had more female pts. A higher proportion of pts in TLNext had received only 2 prior LoT. Overall, M SAT had a higher proportion of pts with factors known to be associated with poorer outcomes in 3L+ FL, e.g. refractory to prior anti-CD20 therapy, double-refractory to prior anti-CD20 therapy and alkylator therapy. The most common regimens in the TLNext cohort were bendamustine-like regimens (34%), PI3K-like regimens (15%), and anti-CD20 monotherapy (14%). Comparative MAIC analyses are ongoing. Image:Summary/Conclusion: TLNext represents a real-world 3L+ FL cohort from Germany that provides relevant context for the M SAT. TLNext outcomes data will be re-weighted using the MAIC approach to generate a descriptive benchmark for outcomes observed in M SAT. While comparisons between clinical trials and RWD carry several limitations pertaining to measurement, reporting of data, and choice of analytical approach to conduct the comparison, RWD from TLNext may be useful to describe a benchmark for clinical practice in 3L+ FL in Germany and globally prior to the availability of randomized evidence on newer treatment options like mosunetuzumab.